T20 states (can't give you page number, sorry) that US $3 = 1 Cr.
I have always worked under the assumption that 1 Cr is an hour of skilled labor [within the Imperial definition of "skilled," i.e., Comp-1, Elec-1, Mech-1, Engn-1, or the T20 equivalents]. Also, this is "human skilled labor," not "robotic labor," which is where that armored, vacc-rated, lunar-capable, 10-ton, etc. ATV is built.
General Products, or your Traveller universe's equivalent, has a robotic factory that churns the things out at 10 per second, and can be re-tooled for different tech levels by the push of a button. (Aren't memory metals grand?) Why does GP, a TL15 megacorporation, make TL9 ATVs? Because the TL9 market world has the capability to make spare parts/fuel/etc. for TL9 ATVs and not TL10 ATVs. Sure, some of the wealthier folks pay to bring in high-tech vehicles (probably mostly TL15 tricked-out speeders), but not the bread-and-butter common folk.
Take televisions in the United States. They were horrendously expensive when introduced. In 1948 (after a few years on the market), they ranged in price from the $100 3" Pilot's TV to the DuMont 20" set for $2495. That's 1948 dollars, there, so up that by an order of magnitude and you get $1,000-$25,000 for a TV. And a crappy TV at that.
Now, you can get a 32" LCD TV for about $1,000 or even less, and if you wanted a 3" TV (in color, even), you could get one to carry around with you for about $200. If you just wanted a no-frills 15" TV, you could probably find one for less than $100.
Now, would General Products put some push-the-envelope features on their ATVs to be marketed on the TL9 world? Certainly! Their ATVs are going to be superior to the home-built ones (TL15 engineering programs ensure that all the kinks are totally worked-out and the materials are superior) and probably be TL 9.1-9.2. Still low enough that the infrastructure on the planet can support them, but high enough to lure the buyer into buying the GP-112XV instead of the local brand.
It's all about mass production and mass consumption....